Assembly to separate liquid from a multiphase flow

ABSTRACT

Assembly to separate out liquid frotfi a multiphase fluid flow, comprising a scrubber, a column, a separator or other conventional separation equipment, combined with a deliquidizer that is connected as a preseparator to the fluid inlet. in that the deliquidizer functions according to a cyclone principle. With the assembly according to the invention the deliquidizer is modified such that it can be combined with conventional separation equipment such that a surprising improved technical effect is achieved. More specific the improved technical effect is achieved for assemblies where the deliquidizer is vertically oriented placed outside conventional separation equipment, with main flow direction upwards or downwards, or with the deliquidizer placed within conventional separation equipment.

FIELD OF THE INVENTION

The present invention regards separation of liquid from a multiphasefluid flow. More specific the present invention regards an assembly toseparate a liquid from a multiphase fluid flow, comprising a scrubber, acolumn, a separator or another conventional separation equipmentassembled with a deliquidizer such that the deliquidizer functions as apreseparator. With the assembly according to the invention reduced spaceand weight are achieved compared to prior art separation assemblies.

BACKGROUND OF THE INVENTION AND PRIOR ART

In process plants in general, and in particular for processing ofhydrocarbons on platforms or vessels offshore, it is essential that theseparation equipment is light, of low volume and is economicalbeneficial compared to the technical effect achieved. To achievebeneficial effects different types of separation equipment can becombined.

In patent application NO 2000 6656, available to the public from 24 Jun.2002, it is mentioned that a deliquidizer (denoted a device), which isthe topic for said patent application, can be combined with otherconventional separation equipment to achieve a beneficial increasedseparation effect. In connection with the assembly of the deliquidizerwith other equipment it is mentioned on page 2, lines 4-7 that “Thedevice according to the invention can be used as an inlet arrangement toscrubbers and separators to improve the effect of such equipment.Further the device can be used as a free-standing unit in pipes andpipelines in oil/gas wells, in pipelines on shore or on the seabed, orin process plants on shore or offshore.” On page 2, lines 35-36 it ismentioned that “The device can be mounted both horizontally orvertically with certain constructional changes.” On page 5, lines 3-6 itis mentioned that “The vessel 16 can e.g. be a separator, a scrubber ora T-pipe element, dependent on the actual utilization. The vessel canoptionally be equipped with a more or less advanced demister, to dry therecirculation gas to an appropriate level, dependent on theutilization.” Eventually it is mentioned on page 5, lines 14-16 that “Bythe simplest utilization of the deliquidizer, e.g. in the inlet to aseparator or scrubber, it will not be any demand for monitoring orcontrol of the device.”

In the above mentioned publication NO 2000 6656 there is no descriptionof the “certain constructional changes” that has to be undertaken forthe deliquidizer to be mounted either horizontally or vertically.Neither is it mentioned that the deliquidizer can be placed withinseparation equipment of conventional type, such that the outlets forliquid and gas both are within the separation equipment.

There is a demand for assemblies for separation of liquid from amultiphase fluid flow, with lower weight, lesser volume and bettertechnical effect.

The aim of the present invention is to meet the above-mentioned demandby providing assemblies between the above-mentioned deliquidizer andequipment of conventional type, in ways novel for the skilled person,including certain modifications of the deliquidizer, to achieve improvedseparation effect, reduced volume and weight, and thereby beneficialtechnical effect.

SUMMARY OF THE INVENTION

The demand is unexpectedly met in that an assembly is provided forseparating liquid from a multiphase fluid flow, comprising a scrubber, acolumn, a separator or other conventional separation equipment combinedwith a deliquidizer that is connected as a preseparator to the fluidinlet, in which deliquidizer the fluid flow is set into rotation so thatit is separated in a central zone along the longitudinal axis, whichcentral zone in substance contains gas, and an outer annular zoneagainst the inside of the outer wall, which outer zone in substancecontains liquid, from which central zone an outlet means for gas isarranged and from which outer zone an outlet means for liquid isarranged, in that the deliquidizer is functioning according to a cycloneprinciple.

The assembly according to the invention is distinguished in that it iscomprising a deliquidizer with

-   -   an in substance pipe formed casing arranged to constitute a        section of the pipeline proper or the inlet, in that a spin        element for rotation of the fluid flow is located at the        upstream end of the casing,    -   an outlet means for gas comprising an outlet element arranged at        the downstream end of the casing, which outlet means has a        central, axial passage way for the gas, and an outer surface        that together with the inner surface of the casing forms an        annulus for inflow of liquid, in that a barrier is formed at the        downstream end of the element for the liquid, and optionally an        antispin element is arranged at the downstream end of the gas        outlet means,    -   an outlet means for liquid comprising an upward open vessel that        is arranged at the downstream end of the casing, or at the        upstream end by main flow direction upwards, which outlet means        is arranged for taking up liquid that flows into the annulus and        partly flows down into the vessel from the bottom region of the        casing at the vessel opening, and partly falls down into the        vessel from the region at said barrier, and    -   an upper section of the outlet vessel and a central part of the        inlet spin element upstream end have been connected by use of a        line, optionally with a regulation valve in the line, for        recirculation of gas that can be entrained by liquid that flows        or falls down into the vessel, in that the spin element has a        central void space and is provided with a number of openings for        outflow of recirculated gas from the void space.

With the assembly according to the invention the deliquidizer ismodified so that it can be combined with conventional separationequipment such that a surprising improved technical effect is achieved.More specific the improved technical effect is achieved for assemblieswhere the deliquidizer is vertically oriented placed outside theconventional separation equipment, with main flow direction upwards ordownwards, or with the deliquidizer placed within conventionalseparation equipment. The deliquidizer with the main flow directionvertical upwards is modified such that it differs essentially from thedeliquidizer according to NO 2000 6656.

The deliquidizer is preferably located within the further separationequipment and constitutes an elongation of the inlet, in that thedeliquidizer preferably has main flow direction vertical upwards orvertical downwards, or the deliquidizer is arranged horizontally withinthe further separation means.

The deliquidizer is preferably arranged outside the furtherseparation-equipment and has main flow direction either verticaldownwards or vertical upwards.

The deliquidizer is preferably arranged with main flow directionvertical upwards, in that the deliquidizer is comprising

-   -   a further casing outside the gas/liquid separation pipe, to        collect separated liquid, and    -   an outer cone for the gas outlet pipe, contributing in turning        the liquid flow 180° in relation to the main flow direction.

DRAWINGS

FIG. 1 illustrates an assembly according to the invention in form of avertically mounted deliquidizer with main flow direction downwards, infront of a three phase separator.

FIG. 2 illustrates an assembly according to the invention where thedeliquidizer is mounted horizontally within a two phase gas scrubber, inelongation from the inlet.

FIG. 3 illustrates an assembly according to the invention with adeliquidizer vertically mounted within a two phase scrubber, with mainflow direction upwards in the deliquidizer.

FIG. 4 illustrates an assembly according to the invention with adeliquidizer mounted vertically within a three phase separator, withmain flow direction downwards in the deliquidizer.

DETAILED DESCRIPTION

Reference is first made to FIG. 1 that illustrates an assembly accordingto the invention, more specific a vertically mounted deliquidizer withmain flow direction downwards, combined with a three phase separator bymounting the deliquidizer in the inlet to the three phase separator.More specific a vertical deliquidizer 1 in the inlet pipe to the threephase separator is illustrated, where a spin element 2 is arranged inthe upstream end, and a gas outlet 3 passing gas from the deliquidizerinto the zone for gas in the three phase separator. Further, the liquidlevel 4 in the deliquidizer is illustrated. A recirculation line 5 withregulation valve is arranged from the outer zone in the deliquidizer,just above the liquid level, to the spin element 2. A liquid outlet 6from the deliquidizer is arranged to pass liquid from the liquid regionin the three phase separator, by use of a pipe with a regulation valve.The three phase separator has in the bottom both an outlet foroil/condensate 7 and an outlet for water 8. In the upper part of thethree phase separator an outlet for gas is provided. Further, the waterlevel 9 in the three phase separator is illustrated, as well as the oillevel 10.

FIG. 2 illustrates an assembly according to the invention, more specifica deliquidizer horizontally mounted as inlet arrangement within avertical oriented two phase gas scrubber. In this case the deliquidizeris quite similar to the deliquidizer according to NO 2000 6656, but inparticular the gas outlet means is modified since the gas outlet isdirectly into the two phase gas scrubber. Equipment is arranged in theupper part of the two phase gas scrubber for collecting dropletsentrained by the gas, more specific demisters or cyclones of knowntypes. On the figure, illustrated horizontally, is the inlet for gas andliquid on the left side, the outlet for gas is from the top of the gasscrubber while the liquid outlet is in the bottom.

Reference is made to FIG. 3 that illustrates an assembly according tothe invention in form of a deliquidizer vertically mounted as inletarrangement within a vertically oriented two phase gas scrubber withmain flow direction upwards in the deliquidizer. In this embodiment thedeliquidizer is modified by a cone 11 arranged around the gas outletfrom the deliquidizer, and also a spreading cone 12 for gas is arrangeddirectly downstream the outlet for gas from the deliquidizer, whichmeans just above the deliquidizer since the main flow direction isvertically upwards. Further, it is arranged an additional outer casing13 outside the gas/liquid separation pipe, to collect entrained liquidthat thereby can flow downwards, which means 180° relative to the mainflow direction in the deliquidizer. On the figure, illustratedhorizontally, is the inlet for gas and liquid in the bottom of the gasscrubber, the outlet for gas is from the top, while the liquid outlet isdown at the left side a little over the bottom.

On FIG. 4 a further assembly according to the invention is illustrated,in form of a deliquidizer arranged in the inlet within a three phaseseparator, in vertical position with main flow direction downwards. Asillustrated the gas outlet from the deliquidizer is essentially modifiedin that it is bent such that it turns upwards and ends in the gas regionin the three phase separator.

The assemblies according to the invention with main flow direction inthe deliquidizer either vertically upwards or vertically downwards, havesurprisingly resulted in improved technical effect compared to otherassemblies. The assemblies according to the invention with adeliquidizer mounted within another separation device have surprisinglyresulted in an improved separation effect in less space than otherassemblies.

1. (canceled)
 2. Assembly according to claim 6, characterized in thatthe deliquidizer is arranged within the additional separation equipmentand has a main flow direction vertically upwards.
 3. Assembly accordingto claim 6, characterized in that the deliquidizer is arranged withinthe additional separation equipment and has main flow directionvertically downwards.
 4. Assembly according to claim 6, characterized inthat the deliquidizer is arranged horizontally and is placed within theadditional separation equipment and constitutes an extension of theinlet thereto.
 5. (canceled)
 6. An assembly for separating out liquidfrom a multiphase fluid flow, comprising: an outer wall; a scrubber; acolumn; a fluid inlet; a deliquidizer that is connected as apreseparator to the fluid inlet, that has a substantially pipe-shapedcasing that forms part of an inlet arrangement, and that operates on theprinciple of a cyclone; a spin element, for rotation of the fluid flow,that is located at an upstream end of the casing, that has a centralvoid space and that is provided with at least one opening for outflow ofrecirculated gas from the void space; a separation apparatus that iscombined with the deliquidizer, fluid flow in the deliquidizer therebyrotating so as to be separated in a central zone along a longitudinalaxis; an annular outer zone against the inside of the outer wall; a gasoutlet from the central zone; a liquid outlet from the annular outerzone; a gas outlet arrangement that has an outlet element that islocated at a downstream end of the casing and that has a liquid barrier,a central, axial gas passageway, an outer surface that, together with aninner surface of the casing forms an annulus for inflow of liquid, aliquid outlet arrangement comprising an upwardly open vessel; a lineconnecting an upper part of the outlet vessel and a central section ofthe inlet spin element for recirculation of gas entrained by liquid thatenters the vessel; in which: the central zone primarily contains gas;the annular outer zone primarily contains liquid; the liquid outletarrangement is provided for up liquid that flows into the annular outerzone and partly flows down into the vessel from a bottom region of thecasing at an opening in the vessel and that partly falls down into thevessel from the vicinity of the barrier; and the deliquidizer is placedwithin additional separation equipment and forms an extension of thefluid inlet.
 7. An assembly as in claim 6, further comprising anantispin element arranged at the downstream end of the gas outletarrangement.
 8. An assembly as in claim 6, in which the liquid outletarrangement is located at the downstream end of the casing.
 9. Anassembly as in claim 6, in which a main flow direction is verticallyupward and the liquid outlet arrangement is located at the upstream endof the casing.
 10. An arrangement for separating out liquid from amultiphase fluid flow, comprising: a scrubber; a column; a fluid inlet;an outer wall; a deliquidizer in which a fluid flow rotates such that itis separated in a central zone along a longitudinal axis, said centralzone primarily containing gas, said deliquidizer operating on theprinciple of a cyclone, being placed within additional separationequipment; a separation apparatus that is combined with the deliquidizerand that is connected as a pre-separator to the fluid inlet; an outerannular zone against an inside surface of the outer wall, said outerzone primarily containing liquid; a gas outlet arrangement leading fromthe central zone; an outer cone for the gas outlet arrangement urgingthe fluid flow to turn approximately 180° relative to a main flowdirection; and a liquid outlet arrangement leading from the outerannular zone; in which: the deliquidizer is arranged with the main flowdirection vertically upwards; and the deliquidizer comprises an outercasing to collect separated liquid.